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491.
Kari Punnonen Tapio Puustinen Christer T. Jansean 《Photochemistry and photobiology》1986,44(5):623-627
[14 C]Arachidonic acid was avidly incorporated into human keratinocytes in culture and following exposure to UVB irradiation of 9 mJ/cm2 (erythemally effective, EE) substantial amounts of 14 C-radiolabel were released from the cells. The release of radiolabel was accompanied by a decrease in the labelling of phosphatidylethanolamine whereas the labelling of triacylglycerols and cholesteryl esters was increased. Keratinocytes produced significant amounts of prostaglandin E2 (PGE2 ) and following UVB irradiation of 9 mJ/cm2 (EE) the formation of prostaglandin E2 was increased.
Etretin (Ro 10-1670), the active metabolite of the antipsoriatic drug etretinate (Ro 10-9359), affected significantly neither the total release of radiolabel induced by UVB nor the formation of prostaglandin E2 . However, in the presence of etretin the UVB irradiation induced transfer of [l4 C]arachidonic acid into triacylglycerols and cholesteryl esters was not increased as much as in the corresponding experiments without etretin. On the basis of the present study it appears that etretin does not interfere with the release of arachidonic acid in amounts which could be related to the therapeutic effects of the combination of retinoids with UVB irradiation (Re-UVB) in the treatment of psoriasis. 相似文献
Etretin (Ro 10-1670), the active metabolite of the antipsoriatic drug etretinate (Ro 10-9359), affected significantly neither the total release of radiolabel induced by UVB nor the formation of prostaglandin E
492.
Roy Kari 《International journal of quantum chemistry》1984,25(2):321-329
This paper examines the numerical performance of the BFGS variable-metric algorithm and compares this performance with that of the DFP , SR1 , and OC algorithms. Numerical results indicate that the BFGS algorithm is far superior to the DFP and SR1 algorithms and comparable to the OC algorithm. Although the BFGS algorithm offers a viable method for the direct determination of localized molecular orbital coefficients, the method is not yet competitive with the more traditional methods. 相似文献
493.
Gourab Kundu Theresa Sperger Prof. Dr. Kari Rissanen Prof. Dr. Franziska Schoenebeck 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(49):22114-22118
We report a new air-stable PdI dimer, [Pd(μ-I)(PCy2tBu)]2, which triggers E-selective olefin migration to enamides and styrene derivatives in the presence of multiple functional groups and with complete tolerance of air. The same dimer also triggers extremely rapid C−C coupling (alkylation and arylation) at room temperature in a modular and triply selective fashion of aromatic C−Br, C−OTf/OFs, and C−Cl bonds in poly(pseudo)halogenated arenes, displaying superior activity over previous PdI dimer generations for substrates that bear substituents ortho to C−OTf. 相似文献
494.
Toro C Passier R Diaz C Tuuttila T Rissanen K Huuskonen J Hernández FE 《The journal of physical chemistry. A》2011,115(7):1186-1193
Herein, we report on the experimental and theoretically study of the linear absorption, electronic circular dichroism (ECD) spectra, as well as the two-photon absorption circular-linear dichroism measurements of three different chiral azo derivatives in dimethylsulfoxide solution. Using potential energy surfaces and frontier orbital analysis, we established the most stable conformation for each molecule and elucidated their different electronic transitions. Our theoretical calculations allowed us to unambiguously identify the spectral position of such transitions and correlate them with the spectral profiles observed in the two-photon absorption spectra. To further elucidate the characteristics of the main electronic transitions in terms of spectral shape and position, we carried out measurements of the polarization dependent two-photon absorption cross sections and determined the two-photon circular-linear dichroism spectra of these azo dyes. 相似文献
495.
Elizabeth Christophy Kari Myli Terrance R. Viegut Jeffrey A. Rzepiela Jeanne M. Hossenlopp 《Journal of photochemistry and photobiology. A, Chemistry》1997,110(3):131-234
The excitation of gas-phase methyl benzoate at 240 nm leads to the observation of phosphorescence. The dispersed phosphorescence spectrum has an assigned origin of 25 270 cm−1 and a prominent C=O progression of 1720 cm−1, consistent with literature reports of gas-phase benzaldehyde spectroscopy. Weaker bands, which correspond to formaldehyde ν17 and ν25, are also evident. Time-resolved IR diode laser absorption spectroscopy has been used to probe formaldehyde. Excitation of methyl benzoate at 222 nm clearly indicates the generation of formaldehyde as a photoproduct. The temporal profile of the formaldehyde signal is consistent with significant nascent vibrational excitation in this product. The ratio of formaldehyde initially in the ground vibrational state to that in the excited vibrational states is estimated to be 0.6 ± 0.1. The proposed elimination mechanisms are analogous to those postulated for the formation of CO2 and acetaldehyde from pyruvic acid. 相似文献
496.
Prof. Dr. Markus Albrecht Dr. Hai Yi Okan Köksal Prof. Dr. Gerhard Raabe Dr. Fangfang Pan Dr. Arto Valkonen Prof. Dr. Kari Rissanen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(20):6956-6963
The ability of multiple CF3‐substituted arenes to act as acceptors for anions is investigated. The results of quantum‐chemical calculations show that a high degree of trifluoromethyl substitution at the aromatic ring results in a positive quadrupole moment. However, depending on the polarizability of the anion and on the substitution at the arene, three different modes of interaction, namely Meisenheimer complex, side‐on hydrogen bonding, or anion–π interaction, can occur. Experimentally, the side‐on as well as a η2‐type π‐complex are observed in the crystal, whereas in solution only side‐on binding is found. 相似文献
497.
498.
499.
Toni Mäkelä Anniina Kiesilä Dr. Elina Kalenius Prof. Kari Rissanen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14264-14272
Synthesis and ion‐pair complexation properties of novel ditopic bis‐urea receptors based on dibenzo[21]crown‐7 ( R1 ) and dibenzo[24]crown‐8 ( R2 ) scaffolds have been studied in the solid state, solution, and gas phase. In a 4:1 CDCl3/[D6]DMSO solution, both receptors clearly show positive heterotropic cooperativity toward halide anions when complexed with Rb+ or Cs+, with the halide affinity increasing in order I?<Br?<Cl?. In solution, the rubidium complexes of both receptors have higher halide affinities compared to the caesium complexes. However, Rb+ and Cs+ complexes of R2 show stronger affinities toward all the studied anions compared to the corresponding cationic complexes of R1 . Similar selectivity of the receptors toward the studied ion pairs was also observed also in the gas phase by competition experiments with mass spectrometry. A total of eight crystal structures with different rubidium and caesium halides and oxyanions were obtained in addition to the crystal structure of R2?BaCl2 . The selectivity observed in solution and in the gas phase is explainable by the conformational differences observed in the crystal structures of ion‐pair complexes with R1 and R2 . In the solid state, R1 has an open conformation due to the asymmetric crown‐ether scaffold, whereas R2 has a compact, folded conformation. Computational studies of the ion‐pair complexes of R2 show that the interaction energies of the complexes increase in the order CsI<CsBr<CsCl<RbCl, supporting the selectivity observed in solution and the gas‐phase. 相似文献
500.